Flexible permanent magnetic materials are often supplied in the form of sheets or rolls and have been commercially available for many years. These materials are typically prepared by mixing a powdered ferrite material with a suitable polymeric or plastic binder into a uniform mixture. The polymeric materials are often elastomers, and the process is therefore typically accomplished through the use of sheet extrusion or calendering. The mixture is converted into strip or sheet form, providing a permanent stable product that is usually somewhat flexible, and that can readily be handled and made into elements of any desired shape by cutting and/or stamping.
The magnetic material is permanently magnetized so that the resulting elements can act individually as permanent magnets, the magnetic field being of sufficient strength that they will adhere to a magnetically attracted surface, such as the surface of an iron or steel sheet, even through a sheet of paper or thin cardboard. Many magnetic materials and the resultant sheet materials are typically inherently dark in color and it is therefore usual to attach these magnets to a printable substrate such as paper or plastic by gluing. It is therefore to the paper or plastic that the decorative pattern and/or other information may be printed. A popular application of such materials is thin, flat magnets having on their outer surface a decorative pattern and/or promotional information, including advertisements in direct mailings, newspaper inserts, and so forth, box toppers, coupons, business cards, calendars, greeting cards, postcards, and so forth.
These magnetic pieces may then be placed on a magnetically attracted surface such as a refrigerator, file cabinet, or other surface where they may be used as reminders and are often used to hold sheets of paper such as notes, recipes, lists, children's artwork, reminders, and so on.
In the usual manufacture of these items, multiple producers are involved in the process. For example, a printer produces the printed matter on wide web presses or individual sheets. If in web form, the web is cut into individual sheets and then shipped to a magnet manufacturer where the magnetic material and the printed matter are joined through the use of an adhesive layer. Alternatively, the printer may purchase or otherwise obtain magnets and then join the printed matter to the magnets through the use of an adhesive layer, or may have both pieces shipped to a third party where the pieces may be joined through the use of an adhesive layer.
There remains a need in the art for an improved magnetic composition which can be applied in such a way that the production process of such flexible magnets can be simplified.